Wired radio system



' Dec. 17, 1929. 7 A. H. TAYLOR WIRED RADIO SYSTEM Filed Jan. 23. 1926 M ATTORNEY Patented Dec. 17, 1929 UNITED STATES PATENT OFFICE ALBERT H. TAYLOR, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO WIRED RADIO, INC., OF NEW YORK, N, Y., A CORPORATION OF DELAWARE WIRED RADIO SYSTEM Application filed January 23, 1926. Serial No. 83,279.

My invention relates broadly to high frequency signaling systems and more particularly to wired radio broadcasting systems.

One of the objects of my invention is to 5 provide a wired radio broadcasting system where the transmission frequencies are maintained constant and operated in such relation that there will be no interference between the channels.

Another object of my invention is to provide a piezo electrical crystal control system for wired radio signaling systems, in which the constant frequency characteristics of piezo electric crystals are utilized for maintaining synchronism between the receiving circuits, that are connected at various points along a wire distribution system, and a central wired radio transmitter.

Still another object of my invention is to provide a three phase wired radio transmission system for operation over three phase power distribution lines, where receiving apparatus connected to different phases of the power distribution line may be maintained in synchronism with the transmitting station by means of piezo electric crystal control circuits.

A further object of my invention is to provide a piezo electric crystal control system for a three phase transmission system connected to a power distribution line with piezo electric crystal receiving circuits distributed at various points in the power distribution line and accurately ground to a frequency 5 corresponding to the frequency of the transmitter, in such manner that simultaneous transmission of three different programs may be conducted on the separate phases and selected by the separate piezo electric crystal controlled receiving circuits for reproduction without interference.

My invention will be more clearly understood from the specification hereinafter following by reference to the accompanying drawing, which shows diagrammatically a wired radio broadcasting system with piezo electric crystal controlled receivers connected at various points in the system in accordance with the principles of my invention.

In wired radio broadcasting systems,

where lectures, news, music, concerts and other entertainment are impressed upon power line distribution systems b carrier frequencies and the energy taken 0 at various points in the power distribution system, it is important that the channels of communication be maintained free of mutual interference and yet the channels must be sufficiently close together to enable the practical utilization of the available wave bands. I have found that the constant frequency electrical characteristics of piezo electric crystals are admirably suited for the control of a wired radio transmission system and for the control of wired radio receivers for mantaining such receivers in synchronism with the transmitting system. I may employ a multiplicity of transmitters, either in single phase or polyphase arrangement, which are used on the same or on dilferent frequencies for the transmission of signaling energy from point to point over an interconnecting power distribution line. The frequency of the transmitters is controlled by the constant frequency oscillations of piezo electric crystals. The crystals may be ground to the same frequency for operating the transmittors in three phase over a three phase power distribution line, or the crystals may be ground at separate frequencies and the transmitters each operated at single phase for transmitting separate programs over the power distribution system.

The output circuts of the transmitters are suitably coupled to impress the high frequency energy on the power distribution line and this energy is conducted over the power distribution system and selected therefrom by receivers each fitted with piezo electric crystal control, where the crystals are ground to frequencies which correspond to the he quencies of piezo electric crystals at the transmitter. The receiving circuits may be operated on all three phases of the power distribution circuit, or the receivers may be connected to selectively receive energy on separate phases of the power distribution line. Vhere desired the wired radio system may be used for distant control of electrical and mechanical apparatus, where a small number of control wires between two points, or the power lines leading from one point to another, may be utilized for the transmission of control signals by carrier currents, where piezo electric crystals are employed for maintaining the characteristics of the transmittin and receiving apparatus in synchronism.

IIeferring to the drawing in more detail, reference characters 1, 2 and 3 indicate electron tubes arranged for the generation of high frequency energy. The electron tubes include grid, filament and plate electrodes, having independent input circuits with their output circuits mutually associated. The input circuit of electron tube 1 is designated by reference character 4 under control of piezo electric crystal 5, positioned between conductive plates 6 and 7. The piezo electric crystal 5 has its conductive plates 6 and 7 connected in the input circuit of the electron tube 1 in series with sensitizing choke 8 and in shunt with the choke 9 and the source of negative potential 10 by which the crystal isoperated under substantially no load for controlling the frequencies of the oscillations developed in the circuits of electron tube 1. Electron tube 2 has its input circuit 13 controlled by piezo electric crystal 11, positioned between conductive plates 12 and 13 and connected in series with a sensitizing choke 15. A shunt circuit including radio frequency choke 16 and source of negative potential 17 is connected across the piezo electric crystal control circuit in a manner similar to the shunt circuit 910 in the input circuit of electron tube 1.

The input circuit 18 of electron tube 3 is controlled by piezo electric crystal 19 positioned between metallic plates 20 and 21 and connected in series with sensitizing choke 22. A shunt circuit comprising radio frequency choke 23 and source of potential 24 is connected across the piezo electric crystal control circuit in a manner similar to the shunt circuits described in connection with electron tubes 1 and 2. The output circuits of the several tubes 1, 2 and 3 contain a common source of plate potential 25 and are connected in A or Y with the circuits of a power amplifier which I have represented as contained within the rectangle 26, the output circuits of which are connected in A or Y and coupled with the transmission line 27 The output circuits may include inductances 28, 29 and 30 each shunted by condensers 31, 32 and 33. The inductances of each of the output circuits of the power amplifier system are coupled with Y connected inductances 34, 35 and 36 capacitively connected through condensers 37, 38 and 39 with the power distribution line 27. Modulation of the system may be secured in any desired manner. The output of the three phase oscillator system may be modulated in the circuits of the power amplifier by any of the usual methods of master oscillator and power amplifier systems and I have represented this diagrammatically by the rectangle 40 and connections 41 with the power amplifier system 26. Any one of the crystal controlled oscillator circuits may connect through independent power amplifier units which are independently modulated when the system is operated with the transmitters operating at different frequencies and on different phases. I have represented a branch circuit 42 extending from the power distribution lines 27 and on this branch circuit any number of subscriber receiver systems may be connected. I have represented a three phase radio receiver system at 43 including Y connected inductances 44, 45 and 46, which are electrically connected with the branch circuit 42 through condensers 47, 48 and 49. The secondary circuit, of the receiver system, includes inductances 50 and 51, tuned by variable condenser 52 with the frequency of the receiving circuit maintained constant by means of a piezo electric crystal 53 positioned between conductive plates 54 and 55, and connected with the receiving circuit. The piezo electric crystal 53 may be ground to the frequency of the piezo electric crystals 5, 11 and 19, where the transmitter is arranged for three phase operation. Where it is desired to separate the broadcasting channels into single phases of a polyphase system, inductances 56, 57 and 58 may be connected with the branch circuit 42 and arranged in A with each of the inductances coupled to inductances 59, 60 and 61 of separate receiver systems. The inductances 59 may be electrically connected to condensers 62 and 63 with inductance 64 which is coupled to inductance 65 connected to a receiving circuit. The receiving circuit is tuned selectively to one of the transmitting channels by means of piezo electric crystal 66 secured between conductive plates 67 and 68, which connect across the winding 65. The frequency of piezo electric crystal 66 may correspond to the frequency of piezo electric crystal 5 and a plurality of similar receiving circuits may be equipped with similar piezo electric crystals. The receiving circuit may comprise any desired number of electron tubes arranged for radio frequency amplification of the received signaling energy, the rectification thereof and the subsequent audio frequency amplification. I have represented a simple regenerative receivin circuit including detector tube 69, wit its input circuit connected with the piezo electric crystal control circuit and tuned by means of condenser 70 with a grid leak and grid condenser 71 in the grid circuit and a coupling coil 72 in the plate circuit thereof. It will be understood that any desired form of receiving circuit may be employed and that theshowing herein is merely for illustrative purposes. The' inductance 60 is ca-' pacitively connected to condensers 73 and 74 with primary coupling coil 75 which connects with the secondary coupling coil 76 arranged in the receiving circuit comprising electron tube 7 7. The frequency of the receiving cir cuit formed by the tube 77 is governed by means of piezo electric crystal 78 positioned between conductive plates 79 and 80. The piezo electric crystal 78 may be ground to a frequency corresponding to the frequency of piezo electric crystal 11 in order that the second channel of communication may be established without interference with respect to the first channel.

The inductance 61 is electrostatically coupled to condensers 81 and 82 with inductance 83, which is in turn coupled to secondary inductance 84. The secondary inductance connects with the receiving circuit formed by electron tube 85. The frequency of this last named receiving circuit is controlled by piezo electric crystal 86 carried between conductive plates 87 and 88, by which the crystal is connected across the receiving circuit. The piezo electric crystal 86 may be ground to a frequency corresponding to the frequency of piezo electric crystal 19 for establishing the third channel of wired radio broadcasting independent of the first and second mentioned channels.

The several receivers may be independently connected to audio frequency amplifier circuits and to any desired form of reproducer. Where desired, repeating systems may be operated in this manner, where the telephone receiver circuit, designated generally at 90 as the output circuit of the receiver which includes electron tube 69, may be connected to control a repeating circuit for re-transmission of the signaling energy at increased amplitude.

It will be understood that where independent transmission on three separate channels is carried out that each channel is modulated independently of an adjacent channel and that by reason of the matched piezo electric crystals at the transmitting and receiving stations the transmission and reception are carried on without mutual interference.

lVhile I have described my invention in certain particular embodiments, I desire that it be understood that modifications may be made and that I intend no limitations upon the invention other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a wired radio broadcasting system the combination of a line wire distribution circuit, a polyphase transmitter of high frequency electrial signals connected with said line wire distribution circuit, a plurality of receivers connected with said line wire distribution circuit for selectively receiving the energy impressed upon said line Wire distribution circuit by said transmitter, and piezo electric control elements ground to the same frequency located in each phase of said transmitter and at each of said receivers for controlling said circuits at the same operating frequency.

2. In a three phase wired radio broadcasting system the combination of a three phase power distribution line, a three phase transmitter of high frequency oscillations connected with said power distribution line, said transmitter including a plurality of electron tubes each having input and output circuits arranged for the generation of high frequency oscillations, a piezo electric crystal arranged in the input circuit of each of said electron tubes for controlling the frequency of the oscillations generated in the circuits of said electron tubes, a plurality of wired radio receivers independently connected with the separate phases of said power distribution line, each of said receivers including an electron tube system having an input circuit and a piezo electric crystal arranged to control the frequency of said electron tube system in accordance with the frequency of said piezo electric crystals at said transmitter.

ALBERT H. TAYLOR- 

